Guidewire-Centering Catheter Tip

ABSTRACT

A catheter for use with a guidewire, the catheter having a distal tip that centers the guidewire even when the catheter is severely bent, thereby avoiding protrusion of the distal tip of the catheter at the outer meridian of the catheter bend and reducing the risk of the catheter tip catching on the luminal surface of the adjacent vasculature. The distal tip of the catheter incorporates at least one guidewire bearing, preferably multiple bearings in the form of longitudinally oriented ribs, which provide the centering characteristic with minimal friction between the inner surface of the catheter distal tip and the outer surface of the guidewire. Preferably, at least four guidewire bearings are provided.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 10/324,714 filed Dec. 19, 2002 (allowed).

FIELD OF THE INVENTION

The present invention relates to the field of catheters intended for usewith guidewires, and more particularly to the distal tip of suchcatheters.

BACKGROUND OF THE INVENTION

Catheters intended for use with guidewires have a distal tip with aninner diameter that is slightly larger than the outside diameter of theintended guidewire. The difference in diameter is necessary to providethe guidewire with operating clearance. When navigating tortuous anatomyor crossing a previously deployed stent, the guidewire is not concentricwith the distal tip of the catheter due to this required clearance.Because of this required clearance, the distal tip of the catheterprotrudes along the outer meridian of a severely bent catheter/guidewireassembly, with the result that it is at risk of catching on the vesselwall and consequently impede trackability of the catheter over theguidewire. This can result in an increase in the time of the procedureas the medical practitioner may be forced to withdraw the catheter andagain attempt to maneuver the assembly through the tortuous anatomyresponsible for the severe bend. Likewise, if the catheter tip catcheson the luminal surface of the vessel wall, damage to the luminal surfacemay result, requiring surgical intervention. Similarly, the catheter tipis also at risk of catching on the struts at the end of a previouslydeployed stent, thereby impeding crossability.

There have been various catheter designs in the art that describecentering concepts that relate to the tip of the catheter. U.S. Pat. No.5,122,125 to Deuss teaches a guiding catheter having a tip portion withexternal ribs intended to center the catheter within the vessel it isbeing moved through. U.S. Pat. No. 6,228,110 to Munsinger describes acatheter with a tip portion including a series of bristles affixed tothe luminal surface of the tip. The bristles are intended to serve as anaxial brake designed to inhibit unintended axial motion between thecatheter and a guidewire within the catheter. The concentric design ofthe bristles serves to center the guidewire within the catheter tip.However, the group of bristles are located some distance proximally fromthe distal end of the catheter, with the result that while an effectiveaxial braking means is provided between the catheter and guidewire, theguidewire is not centered as it exits the distal end of the catheter.

SUMMARY OF THE INVENTION

The present invention relates to centering means provided to the distaltip of a catheter to assure that a guidewire or other device exiting thedistal tip is substantially centered with respect to the distal tip,thereby reducing any risk of the edge of the catheter tip catching onthe luminal surface of a vessel when the tip region of the catheter isseverely bent, as is often the case when traversing tortuous vesselswith the catheter.

The centering means comprises at least one and preferably multiplebearing surfaces located on the luminal surface of the catheter tip.These bearing surfaces preferably take the form of ribs that projectinwardly from the luminal surface of the catheter tip, the ribspreferably being oriented substantially parallel to the longitudinalaxis of the catheter. They are preferably integrally formed on theluminal surface of the catheter tip and consequently are from the samematerial that comprises the catheter tip. Preferably, at least three,and more preferably at least four, such ribs are provided, equallyspaced around the luminal surface of the catheter tip.

To ensure optimal centering, these “bearings” can be formed to provide aslight interference with a guidewire or other device intended to bepassed through the lumen of the catheter. The interference is of such aminimal amount that no perceptible increase in friction between theguidewire and catheter occurs.

The bearings, particularly when they take the form oflongitudinally-oriented ribs, are preferably of a relatively shortlength, extending back into the catheter from the distal tip for alength of, for example, about 6 mm or less, and may be as short as 3 mmor less. The proximal ends of the bearings preferably transitionsmoothly rather than abruptly into the luminal surface of the catheter.In transverse cross section, the ribs preferably have a semi-circularshape.

The catheter tip of the present invention can be used with any catheterthat is placed with a guidewire of any size. Possible applicationsinclude, but are not limited to, cardiology catheters (which aretypically placed over guidewires of about 0.36 mm diameter), urologycatheters (typically placed over guidewires of about 0.89 mm diameter)and radiology catheters (typically placed over guidewires of about 0.97mm diameter).

While it is preferred that the bearings take the form of ribs, otherforms may be used such as hemispherical bumps or an annular ring placedat the luminal surface of the catheter tip.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a transverse cross section of a catheter distal tip andguidewire of the prior art.

FIG. 2 is a side view of a catheter and guidewire of FIG. 1, showing thecatheter in a bent state and showing the resulting “ledge” at thecatheter tip where the guidewire exits.

FIG. 3 is a transverse cross section of a catheter tip of the presentinvention showing bearings projecting from the luminal surface of thecatheter tip.

FIG. 3A is a transverse cross section of the catheter tip of FIG. 3further showing a device such as a guidewire centered within thecatheter tip.

FIGS. 4 and 4A are longitudinal cross sections of catheter tips of thepresent invention, showing the bearings in the form of ribs orientedparallel to the longitudinal axis of the catheter.

FIG. 5 is a longitudinal cross section of a catheter tip of the presentinvention, showing the bearings in the form of ribs oriented helicallywith respect to the longitudinal axis of the catheter.

FIG. 6 is a longitudinal cross section of a catheter tip of the presentinvention, showing the bearings in the form of hemispheres located atthe tip of the catheter.

FIG. 7 is a transverse cross section of an alternative embodiment of thecatheter tip.

FIG. 8 is a transverse cross section of another alternative embodimentin the form of a variation of the tip described in FIG. 3.

FIG. 9 is a transverse cross section of an alternative embodimentwherein wires are embedded in the material of the catheter tip andbearing.

FIGS. 10 and 11 are longitudinal and transverse cross sectionsrespectively of an alternative embodiment wherein a single bearingsurface in the form of a circumferentially oriented raised ring-shapedbearing surface, located at the luminal surface of the distal tip of thecatheter.

FIGS. 12A and 12B describe sequential side views of the catheter tip,with the tip shown in cross section, as used to capture and collapse anembolic filter.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a typical transverse cross section of the tip portion 11 of acatheter 10 of the prior art. A device such as a guidewire 12 iscontained within the lumen of the catheter 10. There is providedclearance, shown as dimension 13, between the inside diameter of the tipportion 11 and the outside diameter of the guidewire 12. As furtherdescribed by the side view of FIG. 2, when the catheter 10 is severelybent as is often the case when traversing tortuous vessels with thecatheter 10 and guidewire 12, the guidewire will offset to the innermeridian of the bent catheter 10. The result is that a ledge 14 iscreated by the wall thickness of the tip portion 11 of the catheter 10in combination with the operating clearance 13 between the guidewire 12and inside diameter of the tip portion 11. It is this ledge 14 thatposes a risk of catching on the luminal surface of the vasculature.

FIG. 3 describes a transverse cross section of a tip portion 11 of acatheter 10 of the present invention. Projecting from the luminalsurface of the tip portion 11 are multiple bearings 30, serving ascentering means for any device, such as a guidewire 12, exiting the tipportion 11. These bearings 30 are preferably located only in the regionof the tip portion 11, with result that the operating clearance betweenthe device and the luminal surface of the catheter 10 is maintained overthe remainder of the length of the catheter 10.

Bearings 30 can be formed to provide a slight interference with aguidewire or other device intended to be passed through the lumen of thecatheter. For example, an inside diameter of the catheter tip asmeasured between two opposing bearings, shown as inside diameter 16, mayinterfere in an amount of about 0.025 to 0.050 mm with the outsidediameter of the intended guidewire. The interference is of such aminimal amount that no perceptible increase in friction between theguidewire and catheter occurs.

FIG. 3A is a transverse cross section of the catheter tip 11 of FIG. 3further showing a device such as guidewire 12 centered within cathetertip 11.

While four bearings 30 are shown, it is apparent that at least three arerequired. At least four are preferred, and more than four may be used,such as five, six, seven, eight, nine, ten, etc.

The transverse cross section of FIG. 3A includes a device such asguidewire 12 shown centered with bearings 30. In a preferred embodiment,there is a slight interference fit between opposing bearings 30 andguidewire 12. Typically, the inside diameter of the catheter tip portion11 as measured between opposing bearings 30 will be slightly less thanthe outside diameter of guidewire 12. For example, for a guidewirehaving an outside diameter of about 0.36 mm (a typical cardiologycatheter), the inside diameter of tip portion 11 as measured betweenopposing bearings 30 will preferably be about 0.31 mm.

The longitudinal cross section of FIG. 4 shows a preferred embodimentwherein bearings 30 take the form of longitudinally-oriented ribs 31,substantially parallel to the longitudinal axis 20 of catheter 10. Thedistal end of the catheter 10 is indicated by arrow 41 and the proximalend is indicated by arrow 42. These ribs 31 are preferably of a lengththat limits them to the tip portion 11 of the catheter 10. A typicallength for ribs extending for the full length of the tip portion 11would be about 3 mm. While their height (as measured perpendicularlyfrom the luminal surface) is maximized at the very distal end of the tipportion 11, they preferably merge into the luminal surface of thecatheter 10 at their proximal end.

Alternatively, as shown by the longitudinal cross section of FIG. 4A,the height of the bearings 30 may be kept substantially constant alongthe full length of each bearing, so that each bearing 30 exerts arelatively uniform force along its entire length against a guidewire orother device inserted through the catheter tip 11.

While the distal end of tip portion 11 is shown to be square, that is,cut off so as to be perpendicular to the longitudinal axis 20 of thecatheter 10, it may be made with various shapes. It is believed that theend should most preferably be round in longitudinal cross section.

In another embodiment shown in the longitudinal cross section of FIG. 5,the bearings may take the form of ribs oriented other thanlongitudinally, such as helically-oriented ribs 33. The longitudinalcross section of FIG. 6 shows still another alternative wherein bearingsare in the form of small protrusions 35 of hemispherical orsubstantially hemispherical shape, located at the very distal end of tipportion 11. It is apparent that various shapes may be used for theprotruding bearing surfaces.

FIG. 7 describes a transverse cross section of an alternative embodimentof the catheter tip 11 wherein the bearings 30 are not of rounded crosssection. Rather, the bearings 30 in this instance are of a shape thatprovides a larger contact area against the surface of the centereddevice.

FIG. 8 shows a transverse cross section of the catheter tip 11representing a variation of the embodiment described by the transversecross section of FIG. 3. FIG. 8 describes relieved areas 81 on theexterior surface of the catheter tip that are directly opposite thebearings 30 on the luminal surface. These relieved areas 81 reduce theresistance of the bearings and allow for a more flexible and less rigidcatheter tip 11.

The bearings are preferably integral to the luminal surface of thecatheter tip, being molded as a part of that surface during themanufacture of the catheter tip. The catheter including the tip withbearings can be fabricated of various materials and combinations ofmaterials known to those of skill in the art of catheters, using methodsknown in this art. These materials include polymers such as amide-basedthermoplastic elastomers, silicones, polyurethanes, polyamides andvarious fluorinated polymers including polytetrafluoroethylene andfluorinated ethylene propylene. Materials of particular durometer may beselected according to the degree of flexibility or rigidity desired. Thecatheter tubing may be reinforced with materials such as braided wiresembedded in the catheter wall.

Alternatively, the bearings may be separately affixed if desired, by,for example, the use of adhesives suitable for the materials involvedand for the medical use. This offers the possibility of providingbearings that have a different degree of flexibility (or rigidity) fromthe material of the remainder of the catheter tip. For example, bearingsmay be made of individual, relatively short pieces of metal wire foradditional tip rigidity and/or radiopacity. The wire can be exposed asthe actual bearing surface. Alternatively, as shown in the transversecross section of FIG. 9, wires 91 may be embedded in the material of thecatheter tip if it is preferred that the exposed bearing surface is thesame material as that of the catheter tip.

FIGS. 10 and 11 describe longitudinal and transverse cross sectionsrespectively of an alternative embodiment wherein a single bearingsurface in the form of a circumferentially oriented raised ring-shapedbearing surface 101, located at the luminal surface of the distal tip ofthe catheter. While the longitudinal cross section shows a semi-circularprofile for the bearing surface, it is apparent that other shapes mayalso be used. While the ring may be continuous around the entirecircumference of the luminal surface, it is apparent that the ring maybe interrupted as with notches to render it into two or morecircumferentially oriented bearing surfaces.

FIGS. 12A and 12B describe sequential side views of the catheter tip(with the catheter 10 and tip 11 shown in cross section) as used tocapture and collapse an embolic filter 121. For this application, thecatheter tip 11 is made from an elastomeric material such as silicone,which allows the catheter tip portion 11 to slightly increase indiameter by stretching to accommodate the capture and collapse of theembolic filter 121 as shown. The tip aids in collapsing the filter 121to a smaller size for removal from the vasculature and ensures thatmaterial captured in filter 121 is also withdrawn via the catheter 10.Bearings 30 are preferably of a more rigid material than the cathetertip 11, providing column strength that prevents the tip 11 from rollinginward and buckling.

While the principles of the invention have been made clear in theillustrative embodiments set forth herein, it will be obvious to thoseskilled in the art to make various modifications to the structure,arrangement, proportion, elements, materials and components used in thepractice of the invention. To the extent that these variousmodifications do not depart from the spirit and scope of the appendedclaims, they are intended to be encompassed therein.

1. A catheter tube comprising a tube for insertion into a body of apatient, said tube having a longitudinal axis, a proximal end, a distalend that is substantially perpendicular to the longitudinal axis of thetube, a lumen extending between the proximal and distal ends allowingpassage of a guidewire therethrough, a luminal surface, and a distal tipportion located adjacent to the distal end of the catheter tube, saidcatheter tube having centering means projecting from the luminal surfaceof only the distal tip portion wherein a distal-most portion of saidcentering means is coplanar with the distal end of the catheter tube,and wherein said lumen provides operating clearance between theguidewire and the luminal surface of the catheter tube over the lengthof the catheter tube exclusive of the centering means.
 2. A cathetertube according to claim 1 wherein the centering means comprise at leastone bearing surface projecting from the luminal surface of the tipportion of the catheter tube.
 3. A catheter tube according to claim 1wherein the centering means comprise at least three bearing surfacesprojecting from the luminal surface of the tip portion of the cathetertube.
 4. A catheter tube according to claim 1 wherein the centeringmeans comprise at least four bearing surfaces projecting from theluminal surface of the tip portion of the catheter tube.
 5. A cathetertube according to claim 1 wherein the centering means comprise multiplelongitudinally-oriented ribs projecting from the luminal surface of thetip portion of the catheter tube.
 6. A catheter tube according to claim1 wherein the centering means comprise multiple helically-oriented ribsprojecting from the luminal surface of the tip portion of the cathetertube.
 7. A catheter tube according to claim 1 wherein the centeringmeans comprise multiple substantially hemispherical shapes projectingfrom the luminal surface of the tip portion of the catheter tube.
 8. Acatheter tube according to claim 1 wherein the centering means extendsback into the catheter tube from the very distal tip for a length of 6mm or less.
 9. A catheter tube according to claim 1 wherein saidcentering means extends back into the catheter tube from the very distaltip for a length of 3 mm or less.
 10. A catheter tube according to claim1 wherein said centering means and said tip portion are integrallyformed of one material.
 11. A catheter tube comprising a tube forinsertion into a body of a patient, said tube having a longitudinalaxis, a proximal end, a distal end that is substantially perpendicularto the longitudinal axis of the tube, a length and a lumen bothextending between the proximal and distal ends, a luminal surface, and adistal tip portion located adjacent to the distal end of the cathetertube, said catheter tube having centering means projecting from theluminal surface of only the distal tip portion wherein a distal-mostportion of said centering means is coplanar with the distal end of thecatheter tube and said centering means has an inside diameter, andwherein, for a device having a maximum outside diameter substantiallyequal to or slightly larger than the inside diameter of the centeringmeans, said lumen allows passage of the device through the entire lengthof the tube.
 12. A catheter tube according to claim 11 wherein thecentering means comprise at least one bearing surface projecting fromthe luminal surface of the tip portion of the catheter tube.
 13. Acatheter tube according to claim 11 wherein the centering means compriseat least three bearing surfaces projecting from the luminal surface ofthe tip portion of the catheter tube.
 14. A catheter tube according toclaim 11 wherein the centering means comprise at least four bearingsurfaces projecting from the luminal surface of the tip portion of thecatheter tube.
 15. A catheter tube according to claim 11 wherein thecentering means comprise multiple longitudinally-oriented ribsprojecting from the luminal surface of the tip portion of the cathetertube.
 16. A catheter tube according to claim 11 wherein the centeringmeans comprise multiple helically-oriented ribs projecting from theluminal surface of the tip portion of the catheter tube.
 17. A cathetertube according to claim 11 wherein the centering means comprise multiplesubstantially hemispherical shapes projecting from the luminal surfaceof the tip portion of the catheter tube.
 18. A catheter tube accordingto claim 11 wherein the centering means extends back into the cathetertube from the very distal tip for a length of 6 mm or less.
 19. Acatheter tube according to claim 11 wherein said centering means extendsback into the catheter tube from the very distal tip for a length of 3mm or less.
 20. A catheter tube according to claim 11 wherein saidcentering means and said tip portion are integrally formed of onematerial.
 21. A catheter tube according to claim 11 wherein the devicecomprises a guidewire.
 22. A catheter tube according to claim 11 whereinthe device comprises an embolic filter.